Optical characterization of CdS semiconductor nanoparticles capped with starch

• Published in: Applied surface science 2010-11, Vol.257 (2), p.581-584
• Main Authors: Rodríguez-Fragoso, P., de la Cruz, G. González, Tomas, S.A., Zelaya-Angel, O.
• Format: Article
• Language: English
• Subjects: Cadmium; Cadmium sulfides; Capping; Clusters, nanoparticles, and nanocrystalline materials; Compact disks; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Materials science; Nanocrystals and nanoparticles; Nanoparticles; Nanoscale materials and structures: fabrication and characterization; Nanoscale materials: clusters, nanoparticles, nanotubes, and nanocrystals; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures; Other topics in nanoscale materials and structures; Photoacoustic spectroscopy; Physics; Raman spectroscopy; Semiconductor nanoparticles; Semiconductors; Starch; Starches; Structure of solids and liquids; crystallography; Vibration mode; X-ray diffraction
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2010.07.036

Starch capped cadmium sulfide (CdS) nanoparticles were synthesized by aqueous solution precipitation. Starch added during the synthesis of nanoparticles resulted in cadmium-rich nanoparticles forming a stable complex with starch. The size of the CdS quantum dots was measured using high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD). The average diameter (d) of nanoparticles spanned the range 4.8±0.4 to 5.7±0.2nm when the pH of the solution was varied within the range 10–14. The main Raman phonon of CdS, the longitudinal optical mode located around 300cm−1, softens as diameter decreases, in accordance with theoretical predictions. In addition, the largest Raman response of starch, near 478cm−1, related with the important skeletal vibration modes of the starch pyranose ring, dominates the spectra of the CdS capped nanoparticles and also softens as the size decreases. This fact indicates a strain variation on CdS as a function of d which increases as the pH increases.